Monitoring the bacterial population dynamics during the ripening of Galician chorizo, a traditional dry fermented Spanish sausage

The dynamics of the bacterial population throughout the ripening of Galician chorizo, a traditional dry fermented sausage produced in the north-west of Spain, were investigated by using classical and molecular approaches.Fermented sausages are certainly complex matrices with PCR inhibitors and background microbiota. Therefore, two different DNA preparation methods were performed to elaborate each standard curve and no significant differences were found, showing a very good correlation between both methods (R2 > 0.994).The combination of the results obtained from microbial counts, species and genus-specific PCR as well as real-time quantitative PCR (qPCR) allowed the identification for the dominant bacterial species and the study of the variation in the community composition over the ripening period. According to the data obtained both by identification of plate isolates and by real-time PCR, the dominant species among staphylococci and lactobacilli were Staphylococcus equorum and Lactobacillus sakei, respectively. However, only real-time PCR assay showed enough sensitivity to detect and quantify staphylococci in meat batter before stuffing, showing values of 5.28 log CFU/g when quantifying Staphylococcus spp. and 2.87 log CFU/g when quantifying S. equorum.In conclusion, real-time PCR was shown to be an efficient tool for the study of the complex associations developed in meat fermentations and for the characterization of dominant populations.

► The article deals on the microbial ecology during the ripening of a Spanish sausage.
► Classical and molecular methods were used to monitor bacterial population dynamics.
► Only qPCR showed enough sensitivity to detect staphylococci in mix before stuffing.
► The dominant species among staphylococci was Staphylococcus equorum.
► The dominant species among lactobacilli was Lactobacillus sakei.